TITLE: Esters of allyl-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid and polymers
thereof
United States Patent 4847335
ABSTRACT:
Compounds of the formula I ##STR1## in which a is 1, 2 or 3, m is an
integer from 2 to 20, R^1, R^2 and R^3 independently of one another are
hydrogen or methyl and R^4 is an m-valent radical of a polyol after
removal of m hydroxyl groups, can be thermally reacted to give
crosslinked polymers having outstanding physical properties.
The polymers are suitable especially as casting resins, matrix resins,
adhesives, encapsulating resins, insulating materials for electronics
and electrical engineering and in surface protection.
INVENTORS:
Kramer, Andreas (Dudingen, CH)
APPLICATION NUMBER: 07/079979
PUBLICATION DATE: 07/11/1989
FILING DATE: 07/31/1987
ASSIGNEE: Ciba-Geigy Corporation (Ardsley, NY)
PRIMARY CLASS: 525/502
OTHER CLASSES: 525/508, 560/120, 560/128
INTERNATIONAL CLASSES: C07C69/74; C08F12/32; C08F36/00; C08F36/20; C08G65/332; H01B3/44;
(IPC1-7): C07C69/74; C08G8/30
FIELD OF SEARCH: 560/1, 560/120, 560/128, 526/321, 525/502, 525/508
US PATENT REFERENCES:
4667003 Crosslinked polymers prepared from allyl or
methallyl-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic acid imides and
bisimides May, 1987 Renner 526/259
4587317 Crosslinked polymers obtainable by cationic polymerization and
formed from unsaturated bicyclic imides May, 1986 Renner 526/259
4579916 Curable mixtures containing an epoxide resin, an imide and a
curing catalyst January, 1986 Schmid et al. 525/502
4515962 Allyl or methallyl-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic
acid imides and bisimides May, 1985 Renner 548/435
3658669 RADIATION CROSSLINKED DINORBORNENE POLYMERS April, 1972 Colomb,
Jr. et al. 204/159.12
3287395 Diels-alder reaction products November, 1966 Chang 260/468
3105839 Bicyclo (2. 2. 1)hept-5-ene-2, 3-dicarboxylic acid anhydrides
October, 1963 Renner 260/346.3
OTHER REFERENCES:
A. G. Gonzalez et al., Tetrahedron Letters, 25, 2697 (1984).
PRIMARY EXAMINER: Pertilla, Theodore E.
Attorney, Agent or Firm:
Hall, Luther A. R.
CLAIMS:
What is claimed is:
1. A compound of the formula I ##STR20## wherein R^1, R^2 and R^3
independently of one another are hydrogen or methyl, a is 1, 2 or 3 and
m is an integer from 2 to 20, and R^4 is an m-valent radical of an
aliphatic polyol or a mononuclear or polynuclear cycloaliphatic or
aromatic polyol or of a novolak after removal of m hydroxide groups, or
is an alkylene glycol or polyalkylene glycol radical after removal of 2
hydroxyl groups, no more than one C--O bond being present per carbon
atom in the radical R^4.
2. A compound of the formula I according to claim 1, wherein R^1, R^2
and R^3 are hydrogen and a is 1.
3. A compound of the formula I according to claim 1, wherein R^4 is a
radical of an aromatic polyol or of a novolak.
4. A compound of the formula I according to claim 1, wherein m is an
integer from 2 to 5 and R^4 is an m-valent C[2] -C -aliphatic, a
mononuclear or polynuclear C[5] -C -cycloaliphatic or a C[6] -C[20]
-aromatic radical, a radical of the formula --CH[2] CH[2] [OCH[2] CH[2]
][n] or of the formula --CH[2] CH[2] CH[2] [OCH[2] CH[2] CH[2] ][n]
with n being an integer from 1 to 10, or is an m-valent radical of the
formula II ##STR21## in which T is methylene, isopropylidene, CO, O, S
or SO[2].
5. A compound of the formula I according to claim 1, wherein R^4 is an
m-valent radical of a phenol or cresol novolak after removal of m
hydroxyl groups.
6. A compound of the formula I according to claim 4, wherein m is 2 and
R^4 is --CpH[2p] -- with p being an integer from 2 to 15, a C[5] -C
-cycloaliphatic radical, a C[6] -C -aromatic radical or a radical
of the formula II.
7. A compound of the formula I according to claim 1, wherein R^4 is
derived from a polyol selected from the group consisting of ##STR22## q
being an integer from 3 to 20.
8. A compound of the formula I according to claim 1, wherein R^1, R^2
and R^3 are hydrogen, a is 1, m is 2 and R^4 is ##STR23##.
9. A compound of the formula I according to claim 1, wherein R^1, R^2
and R^3 are hydrogen, a is 1, m is 2 and R^4 is m-phenylene.
10. A compound of the formula 1 according to claim 1, wherein R^1, R^2
and R^3 are hydrogen, a is 1, m is an integer from 2 to 20 and R^4 is
an m-valent radical of a cresol novolak after removal of m hydroxyl
groups.
DESCRIPTION:
The invention relates to bicyclo[2.2.1]hept-5-ene-2-carboxylic acid
esters, which are substituted by allyl or methallyl and may be
substituted by methyl, with 2- to 20-hydric polyols, to their
preparation, to crosslinked polymers obtainable from them and to the
use of these polymers as casting resins, matrix resins, adhesives,
encapsulating resins, insulating materials for electronics and
electrical engineering, and in surface protection.
Derivatives of allyl-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid are
known. Thus, EP-A 105,024 describes imides of this dicarboxylic acid
and the polymers which can be obtained by thermal polymerization of the
monomers. The polymeric products are suitable, for example, as matrix
resins for composite materials or as insulating materials.
Derivatives of allyl-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid have
been described by A. G. Gonzalez et al. in Tetrahedron Lett. 25(25),
2697-2700 (1984). In addition to the allyl and carboxyl functional
groups, these compounds also contain a hydroxyl group or a chlorine
atom in the 7-position. The paper relates to the synthesis of
stereospecifically 7,7-difunctionalized derivatives of the
bicyclo[2.2.1]heptene system.
In U.S. Pat. No. 3,658,669, various derivatives, inter alia also
esters, of substituted carboxylic acids containing the
bicyclo[2.2.1]heptene radical are described.
U.S. Pat. No. 3,287,395 describes Diels-Alder reaction products of
alkenyl-substituted cyclopentadienes with α,β-unsaturated carboxylic
acids, in particular dicarboxylic acids, and the use of these products,
together with other unsaturated dicarboxylic acids such as maleic acid
and with diols for the preparation of unsaturated polyesters.
The allyl- or methallyl-substituted
bicyclo[2.2.1]-hept-5-ene-2-carboxylic acid esters according to the
invention are valuable starting materials for polymers having
outstanding properties. They are defined by formula I which follows:
##STR2## in which R^1, R^2 and R^3 independently of one another are
hydrogen or methyl, a is 1, 2 or 3, m is an integer from 2 to 20 and
R^4 is an m-valent radical of an aliphatic polyol or a mononuclear or
polynuclear cycloaliphatic or aromatic polyol or of a novolak after
removal of m hydroxyl groups, or is an alkylene glycol or polyalkylene
glycol radical after removal of 2 hydroxyl groups, no more than one
C--O bond being present per carbon atom in the radical R^4.
Preferably, a is the number 1 and R^1, R^2 and R^3 are hydrogen.
R^4 is preferably a radical of an aromatic polyol or of a novolak.
Those compounds of the formula I are also preferred in which m is an
integer from 2 to 5 and R^4 is an m-valent C[2] -C -aliphatic, a
mononuclear or polynuclear C[5] -C -cycloaliphatic or a C[6] -C[20]
-aromatic or araliphatic radical, a radical of the formula --CH[2]
CH[2][OCH[2] CH[2] ][n] or of the formula --CH[2] CH[2] CH[2] [OCH[2]
CH[2] CH[2] ][n]
with n being an integer from 1 to 10, preferably 1 to 5, or is an
m-valent radical of the formula II ##STR3## in which T is methylene,
isopropylidene, CO, O, S or SO[2].
The radicals R^4 can in addition also contain free, unesterified
hydroxyl substituents, but there may at most be one C--O bond or
hydroxyl group per carbon atom in the radical R^4. However, radicals
R^4 which are free of hydroxyl groups are preferred.
An m-valent C[2] -C -aliphatic radical R^4 can be straight-chain or
branched. A mononuclear or polynuclear C[5] -C -cycloaliphatic
radical R^4 can represent monocyclic, bicyclic or even polycyclic
systems which, if desired, can be substituted by up to two C[1] -C[5]
-alkyl groups. The hydroxyl groups of the polyol can also be bonded to
the cycloaliphatic radical via C[1] -C[5] -alkylene groups, for example
methylene.
Examples of suitable aliphatic radicals R^4 are ethylene, 1,2- and
1,3-propylene, butylene, penta- and hexamethylene, heptylene, octylene,
decylene, dodecylene, hexadecylene, neopentylene and radicals of
glycerol, of 1,1,1-tris-(hydroxymethyl)-propane and of pentaerythritol
[2,2-bis-(hydroxymethyl)-1,3-propanediol].
Examples of suitable mononuclear or polynuclear cycloaliphatic radicals
R^4 are cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene,
bis-(cyclohexylene)methane, 2,2-bis-(cyclohexylene)-propane,
decalinylene, bicyclo[2.2.1]heptylene, bicyclo[2.2.2]octylene,
tricyclo[5.2.1.0^2,6 ]decylene and the corresponding C[1] -C[5]
-alkyl-substituted derivatives, or radicals of polyols, in which the
hydroxyl groups are bonded to the cycloaliphatic radical via C[1] -C[5]
-alkylene groups, after removal of the hydroxyl groups. In the case of
a mononuclear or polynuclear C[6] -C -aromatic radical R^4, the
polynuclear systems can also contain fused rings.
Those compounds of the formula I are also preferred in which R^4 is an
m-valent radical of a phenol or cresol novolak after removal of m
hydroxyl groups.
Compounds according to the invention, of the formula I, also comprise
structures in which the radical R^4 is derived from polyols or novolaks
which contain halogen atoms, in particular chlorine and bromine.
Examples of suitable aromatic radicals R[4] are 1,3- or 1,4-phenylene
or naphthylene and radicals derived from bisphenol A or bisphenol F.
Those compounds of the formula I are particularly preferred in which m
is the number 2 and R^4 is a --C[p] H[2p] -group with p being an
integer from 2 to 15, a C[5] -C -cycloaliphatic radical, a C[6]
-C -aromatic radical or a radical of the formula II.
Those compounds of the formula I are very particularly preferred in
which the radical R^4 is derived from a polyol selected from the group
comprising ##STR4## q being an integer from 3 to 20.
That compound of the formula I is most preferred in which a is the
number 1, m is the number 2, R^1, R^2 and R^3 are hydrogen and R^4 is
##STR5##
The compounds according to the invention, of the formula I, can be
prepared in a manner known per se, for example by reacting an acid
chloride of the formula III ##STR6## with a polyol of the formula IV
R^4 (OH)[m] (IV)
in the presence of a quantity, at least equivalent to the acid
chloride, of a tertiary amine or an alkali metal carbonate, the
radicals R^1, R^2, R^3 and R^4 as well as a and m being as defined
under the formula I. The reaction can be carried out without a solvent
or preferably in the presence of an inert aprotic solvent, for example
chloroform, methylene chloride, diethyl ether, dioxane, toluene, xylene
or hexane. Suitable bases for neutralizing the hydrogen chloride
released are tertiary amines, for example triethylamine or pyridine, or
alkali metal carbonates, for example sodium or potassium carbonate. The
reaction temperature can be between 0 and about 150° C. Preferably, the
esters according to the invention are prepared in such a way that the
reactants are brought together at room temperature or with cooling, and
the reaction mixture is then stirred while raising the temperature to
about 50° to 100° C. Preferably, the reaction is carried out with the
use of stoichiometric quantities of the reactants, so that one mol of
the acid chloride III is used per hydroxy equivalent of the polyol IV;
however, an excess of up to 30% of one of the reactants, especially the
acid chloride, can also be used.
The acid chlorides of the formula III can be prepared analogously to
the process described in U.S. Pat. No. 3,105,839, by reacting sodium
cyclopentadienide or sodium methylcyclopentadienide with an allyl or
methallyl halide, followed by a Diels-Alder reaction with acryloyl or
methacryloyl chloride.
Polyols of the formula IV are known or can be prepared in a manner
known per se.
The compounds according to the invention, of the formula I, are liquid
or low-melting solids and are readily soluble in organic solvents. They
can be converted thermally into insoluble crosslinked polymers having
valuable physical properties. No volatile components are formed in the
polymerization, and this is an advantage in many applications, for
example the preparation of coating films or in the use as matrix
resins.
The invention therefore also relates to polymers which are obtainable
by heating a compound of the formula I or a mixture of such compounds
to a temperature between 150° and 300° C., in particular between 180°
and 250° C., for a period of 5 to 30 hours, preferably 10 to 25 hours.
A polymer having particularly advantageous properties is obtained by
heating a compound of the formula I, in which a is the number 1, m is
the number 2, R^1, R^2 and R^3 are hydrogen and R^4 is ##STR7## to a
temperature between 180° and 250° C. for a period of 10 to 25 hours.
The compounds according to the invention can be used and polymerized
directly, or they can first be dissolved in an organic solvent such as
toluene, xylene, methyl ethyl ketone, ethylene glycol dialkyl ethers
having 1-4 C atoms in the alkyl groups or a similar solvent
conventional in the coating industry. Such solutions can be used as
impregnating agents or coating agents or can also be despatched as such
to the user. Preferably, the polymerization of the esters according to
the invention is carried out directly without use of solvents.
Of course, inert and stable substances, such as fillers, pigments, dyes
and other additives, can be added to the compounds of the formula I,
before they are polymerized to give crosslinked structures.
The polymeric products can be used in many ways, for example as
adhesives and also in surface protection and as encapsulating resins
and insulating materials for electronics and electrical engineering,
and especially as casting resins or matrix resins for fibre-reinforced
composites. The low melt viscosity allows impregnation of the fibres
from the melt. Particularly suitable reinforcing agents are
glassfibres, carbon fibres and polyamide fibres. The invention also
relates to the use of the polymeric products for the abovementioned
purposes.
PREPARATION EXAMPLES
Example 1
Allylbicyclo[2.2.1]hept-5-ene-2-carbonyl chloride
##STR8##
A solution of 400 g of NaOH in 800 ml of H^2 O and 16 g of
benzyltriethylammonium chloride in 32 ml of ethanol is warmed to
30°-35° C., and 264 g of cyclopentadiene are added with stirring within
15 minutes. 336 g of allyl chloride are added dropwise to the deep-red
clear emulsion within 45 minutes. A reaction starts immediately, which
manifests itself by evolution of heat and precipitation of sodium
chloride. The internal temperature is maintained between 50° and 55° C.
by means of an ice bath. After the dropwise addition of the allyl
chloride, the mixture is stirred for a further 30 minutes at 50° C. The
reaction solution is cooled down, and 200 ml of water are added. The
salt which has precipitated goes thus into solution. The aqueous phase
is separated off, and the organic phase is washed twice with saturated
NaCl solution and filtered over sodium sulfate. The unconverted
cyclopentadiene and allyl chloride are distilled off at room
temperature and under a reduced pressure. This purification operation
is stopped as soon as an absolute pressure of 33 mbar is reached.
Analysis of the residue by chromatography shows that, in addition to
allylcyclopentadiene (about 75%), di- and tri-allylcyclopentadiene,
dicyclopentadiene and diallyldicyclopentadiene are also present as
by-products. 360 g of crude allylcyclopentadiene are taken up in 400 ml
of methylene chloride. 252 g of acryloyl chloride are added to this
clear red-brown solution within one hour at 20°-25° C. with ice cooling
and the mixture is then stirred for 2 hours at 20° C. The reaction
solution is concentrated in a rotary evaporator and the residue is
distilled under an absolute pressure of 26 mbar. 377 g of
allylbicyclo[2.2.1]hept-5-ene-2-carbonyl chloride pass over between
112° C. and 120° C., which corresponds to a yield of 68% of theory. The
yellow liquid can be stored under nitrogen at 0° C. for a prolonged
period. For characterization, the acid chloride is converted into the
corresponding methyl ester.
Example 2
Hexamethylene bis-(allyl-bicyclo[2.2.1]hept-5-ene-2-carboxylate)
##STR9##
58.9 g of allylbicyclo[2.2.1]hept-5-ene-2-carbonyl chloride (prepared
according to Example 1) are added dropwise at 20° C. within 40 minutes
to a solution of 15.1 g of hexanediol in 150 ml of pyridine. The
mixture is then stirred for a further hour at 80° C. The reaction
solution is cooled down, poured with stirring onto 1,000 ml of 2N HCl
and extracted with twice 250 ml of methylene chloride. The combined
organic phases are washed with 1N HCl, aqueous soda solution and
saturated sodium chloride solution, dried over sodium sulfate and
filtered, and the solvent is distilled off at 60° C. in a rotary
evaporator. The residue is dried for 2 hours at 140° C. in vacuo. This
gives 55.7 g (99% of theory) of a red-brown liquid resin with η
=109 mPas. By gel permeation chromatography (THF) the molecular weight
is found to be 449 (M[n]) or 455 (M[w]).
______________________________________
Analysis: % C % H
______________________________________
Calculated for C H[38] O[4]
76.68 8.73
Found 77.32 8.77
______________________________________
Examples 3 to 10
Analogously to Example 2, various diols are reacted with
allylbicyclo[2.2.1]hept-5-ene-2-carbonyl chloride to give the
corresponding diesters. The results are summarized in Table 1.
TABLE 1
_______________________________________________________________________
___
Ex- Softening Elemental analysis am- Yield Viscosity Point GPC* in THF
(calculated values) ple Diol in % in mPas in °C. --M[n] --M[w] % C %
_______________________________________________________________________
___
H
3 HO(CH[2]) OH 82 145(25° C.)
-- 583 594 78.09(78.12)
9.48(9.64)
##STR10## 97 478(40° C.)
-- 450 455 79.07(79.03)
8.44(8.58)
5
##STR11## 81 237(80° C.)
-- 540 548 80.60(80.99)
7.34(7.35)
6
##STR12## 83 548(80° C.)
-- 641 667 71.66(71.56)
6.06(6.01)
7
##STR13## 91 805(25° C.)
-- 435 448 77.74(78.11)
6.82(7.02)
8
##STR14## 82 166(120° C.)
-- 801 812 76.98(77.27)
6.44(6.48)
9 Phenol novolak 87 1070(80° C.)
-- 818 1351
80.37(81.17)
6.80(6.81)
##STR15##
10 Kresol novolak 97 -- 60 1221
1850
80.91(81.39)
7.13(7.19)
##STR16##
_______________________________________________________________________
___
*Gel permeation chromatography
Example 11
Bisphenol A
bis-(methallyl-methyl-bicyclo[2.2.1]hept-5-ene-2-carboxylate)
##STR17##
(a) Replacing cyclopentadiene and allyl chloride by
methylcyclopentadiene and methallyl chloride and proceeding in other
respects in the same way as described in Example 1,
methallyl-methyl-bicyclo[2.2.1]hept-5-ene-2-carbonyl chloride is
obtained.
(b) 175 g of methallyl-methyl-bicyclo[2.2.1]hept-5-ene-2-carbonyl
chloride are added dropwise at 20° C. within 30 minutes to a solution
of 87 g of bisphenol A in 300 ml of pyridine. The mixture is then
stirred for a further hour at 80° C. and then worked up as described in
Example 2. This gives 205 g (89% of theory) of a brown, liquid resin
with η[120] =640 mPas. By gel permeation chromatography (THF), the
molecular weight is found to be 616 (M[n]) or 656 (M[w]).
______________________________________
Analysis: % C % H
______________________________________
Calculated for C H[48] O[4]
81.42 8.00
Found 80.65 8.04
______________________________________
Example 12
Bisphenol A bis-(allyl-bicyclo[2.2.1]hept-5-ene-2-methyl-2-carboxylate)
##STR18##
(a) The allylcyclopentadiene prepared according to Example 1 is reacted
with methacryloyl chloride instead of acryloyl chloride in the manner
described in Example 1, to give
allylbicyclo[2.2.1]hept-5-ene-2-methyl-2-carbonyl chloride.
(b) 211 g of allyl-bicyclo[2.2.1]hept-5-ene-2-methyl-2-carbonyl
chloride are added dropwise at 20° C. within 40 minutes to a solution
of 114 g of bisphenol A in 350 ml of pyridine. The mixture is then
stirred for a further hour at 80° C. and then worked up as described in
Example 2. This gives 250 g (87% of theory) of a viscous, red-brown
resin with η[120]° =380 mPas. By gel permeation chromatography (THF)
the molecular weight is found to be 675 (M[n]) or 1,183 (M[w]).
______________________________________
Analysis: % C % H
______________________________________
Calculated for C H[44] O[4]
81.21 7.69
Found 80.51 7.55
______________________________________
Example 13
Bisphenol A bis-(diallyl-bicyclo[2.2.1]hept-5-ene-2-carboxylate)
##STR19##
(a) Under the same reaction conditions as in Example 1, 132 g of
cyclopentadiene and 321 g of allyl chloride are added dropwise to 300 g
of NaOH in 600 ml of H[2] O and 12 g of benzyltriethylammonium chloride
(dissolved in 24 ml of ethanol). After the dropwise addition, the
mixture is stirred for 2 hours at 65° C. The salt formed is dissolved
by the addition of water, and the phases are separated. The organic
phase is washed twice with saturated NaCl solution and filtered over
sodium sulfate. Distillation of the red-brown filtrate in vacuo gives
135 g of diallylcyclopentadiene; boiling point: 70°-82° C. at 20 mm.
______________________________________
Analysis (diallylcyclopentadiene): % C % H
______________________________________
Calculated for C H[14]
90.35 9.65
Found 90.18 9.61
______________________________________
81 g of diallylcyclopentadiene are dissolved in 200 ml of methylene
chloride. 45 g of acryloyl chloride are added dropwise to this solution
at 20° C. within 30 minutes and the mixture is then stirred for 1 hour
at room temperature. Distillation of the reaction product gives 84.4 g
(73% of theory) of diallyl-bicyclo[2.2.1]hept-5-ene-2-carbonyl
chloride; boiling point=125°-134° C. at 20 mm.
______________________________________
Analysis: % Cl
______________________________________
Calculated for C H[17] ClO
14.98
Found 14.10
______________________________________
(b) 130 g of diallyl-bicyclo[2.2.1]hept-5-ene-2-carbonyl chloride are
added dropwide at 20° C. within 30 minutes to a solution of 62.7 g of
bisphenol A in 200 ml of pyridine. The mixture is then stirred for 1
hour at 80° C. and then worked up as described in Example 2. This gives
162 g (95% of theory) of a brown, liquid resin with η =3,165 mPas.
By gel permeation chromatography (THF), the molecular weight is found
to be 610 (M[n]) or 691 (M[w]).
______________________________________
Analysis: % C % H
______________________________________
Calculated for C H[48] O[4]
82.13 7.69
Found 81.63 7.85
______________________________________
APPLICATION EXAMPLES
Example A
The diester prepared according to Example 2 is poured as hot, mobile
resin into a test tube and cured for 3 hours at 200° C., 3 hours at
220° C. and 12 hours at 250° C. This gives a clear solid having a glass
transition point of 135° C.
On adhesive bonding of aluminium sheet under the same curing
conditions, the two sheets which are to be adhesively bonded
overlapping by 25×12 mm^2, a tensile shear strength according to ISO
4587 (measurement at room temperature) of 10.9 N/mm^2 is obtained.
Example B
The diester prepared according to Example 5 is cast as a hot, mobile
resin into a steel mould of 8×6×0.4 cm^3 size and cured for 4 hours at
180° C., 5 hours at 200° C. and 10 hours at 220° C. After cooling, test
bars are cut from the clear, red-brown plate. The following properties
are measured on the latter:
______________________________________
Impact bending strength according to VSM 77,105 = 9.6 kJ/m^2 Glass
transition point Tg = 184° C. (measured by TA 2000)^1 10% Weight loss^2
= 405° C. Tensile shear strength (ISO 4587) = 7.4 N/mm^2
______________________________________
^1 TA 2000 = TA 2000 differential thermal analysis system from Mettle
AG, Greifensee, Switzerland. ^2 Measured by heating a sample in TA
2000; determination of the temperature at which 10% of the sample has
volatilized; heating rate 4° C./minute (in air).
Example C
The diester prepared according to Example 7 is cured in a test tube for
4 hours at 180° C., 5 hours at 200° C. and 10 hours at 220° C. This
gives a clear, transparent solid having a glass transition point of
231° C.
Example D
The diester prepared according to Example 10 is cast into a steel mould
of 8×6×0.4 cm^3 and cured as in Example B.
______________________________________
Impact bending strength (VSM 77,105) = 4.9 kJ/m^2 Glass transition
point Tg = 305° C. 10% Weight loss = 438° C.
______________________________________